1. Field of the Invention
This invention relates to a photoconductive member for use in electrophotography, and more particularly to a novel construction of the photoconductive member for use in electrophotography capable of preventing flow and blur of images.
2. Description of the Prior Art
In recent years, as a substitute for inorganic photoconductive materials (hereinafter photoconductive material is often called photoconductor) such as Se, Cds and ZnO, or organic photoconductive material such as poli-n-vynil carbozol and trinitrofluorenone, amorphous silicon photosensitive member using hydrogenated amorphous silicon layer as a photoconductor have become noted for use in electrophotography because of their excellent heat resistance property, wear resistant property, harmless property and high photosensitivity.
As the amorphous silicon type photoconductor for use in electrophotography, a photoconductor comprising an aluminum supporting member and an amorphous silicon layer formed thereon to act as a photoconductive layer has been widely used. However, since the adhesive force of the amorphous silicon to aluminum is not sufficiently large, we have succeeded to improve the adhesive property by subjecting the surface of an aluminum layer 11 to an almite treatment (oxidation treatment) to form a porous layer 12B formed of an anhydrous amorphous aluminum layer whose surface containing numerous fine pores and then applying a hydrogenated amorphous layer 13 to the porous layer 12b without sealing the fine pores as shown in FIG. 6.
Then an amorphous boron layer 14 (a-BN) is applied to the upper surface of the hydrogenated amorphous silicon layer. The amorphous boron nitride layer 14 has properties of an excellent insulating strength and a small light absorption, and can prevent light reflection and is not influenced by environment condition variation.
In the art of electrophotography, the recording of images is made in the following manner. More particularly, after applying uniform electric charge onto the surface of a photoconductor by using corona discharge, a light image is projected. Due to the absorption of the projected light, electron-hole pairs are formed in the photoconductive layer and the electrons and holes thus formed are caused to migrate due to the surface charge so as to cause to remain the surface charge only at regions not irradiated or exposed to light (formation of a latent image). When an oppositely charged toner is sprinkled onto the latent image thus formed, the remaining surface charge attracts the toner through the photoconductor layer and the insulative amorphous boron nitride layer, thus developing or visualizing the latent image. Then the developed toner image is transfer printed onto a copying paper. At this time, there is a tendency of flow or blur of the image, thus failing to obtain a clear copy.
Although it is considered that this is caused by the decrease of the electrostatic attractive force due to the presence of the photoconductive layer and the surface layer, this cause has been considered impossible to eliminate.